Hitherto, there have been known various methods for the production of organosilicones containing epoxy groups. Representatives thereof are the method of causing an olefinic group-containing siloxane to undergo a peroxidation reaction (e.g., peroxidizing vinylsiloxane with a 40 % peracetic acid solution), the method of epoxidizing the siloxanes which have in advance undergone a Grignard reaction, e.g., those having the group of formula .tbd.SiCH.sub.2 MgBr, through an alkali treatment in the presence of epichlorohydrin, the method of reacting chlorosilane or acetoxysilane with glycidol to produce glycidyl silicone ether (U.S. Pat. No. 2,730,532), and so forth.
However, those methods all are disadvantageous in that they are low in yield, require troublesome operations, and cannot secure consistent production.
For an industrial purpose, on the other hand, the monomers, oligomers and polymers of epoxysilicones are generally produced by the addition reaction (hydrosilylation reaction) between olefin epoxides and Si--H containing siloxanes or silanes in the presence of platinum catalyst or a catalyst for hydrosilylation use which contains platinum as a main component (Japanese Tokko Sho 43-25926, and Japanese Tokkai Sho 56-38350 and Hei 3-128975, wherein the term "Tokko" as used herein means an "examined patent publication" and the term "Tokkai" as used herein means an "unexamined published patent application").
However, the platinum catalysts are known to function not only as catalyst for the addition reaction between an olefin and Si--H but also as catalyst for the ring-opening polymerization of epoxides in the presence of Si--H.
More specifically, Japanese Tokkai Hei 3-152128 discloses the method of promoting the ring-opening reaction of epoxides by use of platinum catalyst or a catalyst containing platinum as a main component. In addition, that reference recites acetonitrile, methanol and 2-methyl-4-butene-3-ine as materials acting so as to inhibit epoxides from undergoing the ring-opening reaction. However, it has no description of the method for the production of epoxy-modified silicones.
At present the production of an epoxy-modified silicone is carried out adopting the method in which the batch temperature and the feeding speed of an olefin epoxide are carefully controlled during the reaction and, what is more, a small amount of mercaptan is used for deactivation of a platinum catalyst at the conclusion of the hydrosilylation reaction; or the method of causing the addition reaction between an olefin epoxide and Si--H in the presence of a rhodium catalyst (Japanese Tokkai Hei 4-352793).
However, inhibition of the gelation during the reaction is insufficient in the former method, while in the latter method the reaction rate is difficult to control and a long time is required to complete the reaction.
With respect to other methods for production of epoxysilicones having high polymerization degrees, there are known the method of causing an alkali equilibrium reaction between an epoxy-containing siloxane and an epoxy-free siloxane in the presence of water in a saturated condition (Japanese Tokko Sho 51-33839), the method of causing an alkali equilibrium reaction between the foregoing siloxanes in the presence of an aprotic organic solvent (Japanese Tokkai Hei 3-255130), and so on.
Therein, however, only the addition reaction in the presence of a conventional platinum catalyst, which is capable of causing gelation through the ring-opening polymerization of an epoxy group, is instanced as a method applicable to the production of the epoxy-containing siloxane used as an intermediary raw material.
As a result of our intensive studies of the above-described problems, it has now been found that the gelation arising from the ring-opening polymerization of an epoxide in the addition reaction between an ethylenic unsaturated group-containing epoxide and a Si--H group-containing siloxane or silane in the presence of a platinum catalyst can be inhibited when a lower alcohol is added, thereby achieving the present invention.